The invention relates to a device for piping of process systems in the food and beverage industry, and a method for operating such a device; these piping systems are used e.g. in particular where the process equipment employed for product treatment and product transfer is subject to high microbiological quality requirements and requirements for excellent cleanability in place (so-called “CIP capability”—Clean In Place). The application relates to areas of technology such as dairy technology, pharmaceutical technology, and biotechnology.
The general prototype of such a piping system is disclosed, e.g., in DE 101 08 259 C1, but this is limited to a piping device wherein a so-called valve distributor tree is associated with a tank of a tank farm, opens out directly from the lower bottom of the tank, and has an upwardly oriented, typically vertical course. The process lines and function valves are attached directly below the respective tank outlet. This piping system has proved itself in practice, over time; it is described in more detail in a publication of the firm GEA Tuchenhagen Brewery Systems entitled “ECO-Matrix®, 223d-10/06”; it is designated ECO-Matrix®, and descriptions are provided of the economic benefits provided and the influence on product quality.
In the abovementioned piping system, the function valves may be attached laterally on the tank outlet tree (the so-called valve distributor tree) or vertically on the bottom flange of the tank. This piping technology significantly minimizes the formation of contamination and its later distribution in the process system. The piping system built separately from the tank makes possible a complete product discharge and independent cleaning, independently of the tank.
The valve distributor tree is designed as an elongated hollow body oriented essentially vertically and having connection openings for connecting its inner spaces to pipelines of a piping system which extend laterally past the valve distributor tree. A valve that is mix-proof in its seat region is disposed in each connection between the pipeline and the associated connection opening, and said valve switches this connection in immediate proximity to the hollow body. As an anti-mixing valve a so-called double seat valve which has two closing members movable relative to each other, or a so-called double seal valve which has two seals separated in the stroke direction on a single closing member, or a so-called leak-proof disk valve can be used. Between the axially separated sealing locations of the anti-mixing valve there is a leakage space which is connected via at least one connection path with the surroundings of the anti-mixing valve.
As a preferred anti-mixing valve, the abovementioned double seat valve has been used for some time in piping systems of the type described, which valve has valve rods which are disposed concentrically one inside the other, as the closing members, which rods pass on one side through the valve housing and out of it to the location of a drive means. A double seat valve with such a closing member and valve rod configuration is known from U.S. Pat. No. 4,436,106 A. The leakage space disposed between the two closing members is drained via a leakage discharge between the valve rods of the independently driven first closing member and a hollow rod of the dependently driven second member, which hollow rod surrounds the valve rod. The second closing member is designed as a seat disk in the form of a conical closing sleeve that at its end facing the first closing member bears an axial seat seal which cooperates with the valve seat on the valve housing. The first closing member is also designed as a seat disk, which cooperates with a conical valve seat.
In EP 0 625 250 B1, a double seat valve generally according to U.S. Pat. No. 4,436,106 A is described, wherein the first closing member is formed with a radial sealing means and the second closing member is formed with the known axial sealing means. In the closed position of the valve, the radial sealing means is sealingly accommodated in a cylindrical seat surface, and the end of the second closing member directed toward the first closing member, which second closing member is in the form of a hollow rod, bears the axial seat seal which acts on a seat surface on the valve housing. In EP 0 625 250 B1, with reference to the general double seat valve according to U.S. Pat. No. 4,436,106 A it is stated (see Col. 2 line 56 to Col. 3 line 16) that such double seat valves, starting from the configuration in FIGS. 1 and 2 of U.S. Pat. No. 4,436,106 A, can essentially be disposed in any installation orientation, thus e.g. rotated by 180°, thus with vertically downwardly oriented valve rods, or even in a horizontal or inclined orientation. In the case of downwardly oriented valve rods, with this term also including an inclined orientation of the valve rods, the leakage fluid can independently, freely drain off under the influence of gravity (via the annular gap between the valve rod and the hollow rod) (FIG. 2).
WO 98/54494 A1 discloses a double seat valve for the food industry, wherein the second closing member, in the form of a hollow rod, has on its outer side an axially and/or radially acting second seat seal and on its inner side a cylindrical accommodating bore, on its end segment directed toward the first closing member, which first closing member is in the form of a sliding plunger and is independently actuatable. The end section receiving the accommodating bore extends somewhat beyond the second seat seal, and the accommodating bore is formed with the same diameter as a cylindrical first seat surface, which surface cooperates with a radially acting first seat seal of the first closing member. Due to the axial spacing of the second seat seal from the end-face-side bounding surface of the end section of the second closing member, the seat seals, and with them the associated seat surfaces, do not directly adjoin each other, but rather are connected together by a relatively long, angled gap. In the closed position of the second closing member, the accommodating bore and the first seat surface have moved flush against each other.
A general pipe branching arrangement described in DE 10 2005 051 467 A1 is based on a device system according to DE 101 08 259 C1, and in this system associates an anti-mixing valve with the connections of the hollow body, wherewith the first closing member of the valve is independently driven, and in its opening movement it sealingly comes to abut against the second closing member, which is in the form of a seat disk, and also carries this (the second closing member) into the open position. The second closing member has a second seat seal on its end directed toward the first closing member, which second seat seal cooperates with a second seat surface which adjoins a cylindrical first seat surface. The first closing member, in the form of a sliding plunger, has a radially acting first seat seal, which in the closed position of the valve is sealingly accommodated in the first seat surface. The valve rods for the closing members are disposed mutually concentrically, and are guided through, and out of, the valve housing on one side.
Thus the valve according to DE 10 2005 051 467 A1, similarly to that of EP 0 625 250 B1 with reference to U.S. Pat. No. 4,436,106 A, being disclosed under the point of view of the generally possible installation arrangement, is oriented at an incline to the hollow body, and has, in addition to the radial sealing means on the first closing member and the axial sealing means on the second closing member, a so-called middle seal, which in the open position of the double seat valve is operatively disposed between the two closing members and is disposed at the second closing member. Due to the inclined orientation, the leakage space of the valve has a peripheral wall that extends from a connection-side inlet up to an outlet-side leakage outlet opening which is at a distance from the inlet, which peripheral wall is inclined in the direction of the gravitational force toward the leakage outlet opening. The aim of this measure is to provide means of automatic discharge of leakage fluid collecting in the leakage space, from said leakage space.
The known pipe branching arrangement according to DE 10 2005 051 467 A1, along with that according to DE 101 08 259 C1, is limited to an arrangement in which the hollow body (valve distributor tree) is associated with a tank in a tank farm, and opens out directly from the bottom of said tank. The automatic drainage of the leakage space is only attained (DE 10 2005 051 467 A1) if the double seat valve is disposed in the necessary inclined orientation at the hollow body, i.e. when the peripheral wall of the leakage space has a sufficient slope. Considering the design of the second closing member in the form of a conical closing sleeve, this requires a significant angle of inclination of the longitudinal axis of the double seat valve with respect to horizontal. The inclined connection of the double seat valve at the hollow body mandates, in each case, radially oriented, circumferential protrusions at the latter that form dead zones for the flow in the longitudinal direction of the hollow body. With flow through the hollow body, this results in disruption of the [laminar] flow at these locations, and in turbulence. These protrusions are difficult to clean in the flow passage.
Further, the so-called middle seal is a major drawback, because it makes the valve more expensive and more apt to malfunction, and in the course of the opening and closing movements, particularly in the so-called “engagement position” of the second closing member when engaged by the first closing member, it makes less satisfactory the desired maximally leakage-free switching of the double seat valve, because of cavern formation between the three seals. Furthermore, in the known double seat valve, the seat cleaning flow arising during the respective seat cleaning of one closing member is directed onto the seal region of the other closing member in its closed position, which other closing member, as a rule, is exposed to the product. This direct impact on the seat region by the respective seat cleaning flow is undesirable because it leads to a conversion of the kinetic flow energy into static pressure, whereby, in the case of defective seat seals, leakage flows of the cleaning agent are generated, which come to flow into the valve housing that is exposed to the product.
In the USA, for example, it is required in the case of larger seal defects, or even with a loss of one of the two seat seals, that in the course of the seat cleaning of the respective other closing member no cleaning agent is permitted to pass through via the respective seal defect or the seat region without a seat seal. Under these conditions, such a double seat valve does not only have to meet the requirement to limit the quantity of cleaning agent and to avoid a direct impact of the seat region in the course of the seat cleaning, but also the requirement to withdraw the seat cleaning flow in a condition which is as turbulence-free as possible, initially into the leakage space and from there into the surroundings, without the seat cleaning flow directly flowing against the respectively closed seat area or increasing the pressure on it. This case concerns so-called “PMO capability”, which means that the anti-mixing double seat valve is required to be in operation 365 days a year without interruptions for cleaning, and in the process is capable of seat cleaning on one side, while the other side remains in contact with the product and is thus closed.
In traditional piping systems of the type described initially supra, which were the starting point for the so-called ECO-Matrix® piping systems, and in the latter, primarily high technology leak-proof valves (the above-described double seat valves or so-called double seal valves) are employed; as mentioned, these are referred to as “anti-mixing valves”. A double seal valve is a valve with a single closing member having two axially separated sealing locations, between which the above-described leakage space is disposed. These two leak-proof stroke valves combine all necessary characteristics which presently can be required of a process valve in the area of application under consideration, wherewith if necessary also so-called “seat cleaning” is one of the features. These stroke valves are costly to fabricate and thereby cost-intensive, however.
DE 101 08 259 C1 also identifies as suitable anti-mixing valves so-called “disk valves” having two seals disposed at a distance apart on the sealing surface of the closing member, which closing member is in the form of a disk element, wherewith a leakage space which extends around in a ring shape is disposed between said seals, which leakage space is connected with the surroundings of the disk valve via at least one connection path. DE 101 08 259 C1 does not contain additional information as to how specifically the known piping system is to be realized in connection with leak-proof disk valves.
The present invention expands on the concept of the anti-mixing valve in the form of a disk valve, in that it proposes that disk valves having two separate closing members, each in disk form, axially separated from each other, be employed, wherewith these two closing members are actuated simultaneously or with a time lag, wherewith each closing member forms a sealing location with the associated housing segment, and wherewith a leakage space is provided between the two axially separated sealing locations, which leakage space is connected with the surrounding of the valve via at least one switchable connection path (see, e.g., DE 28 47 038 C3; DE 29 48 534 C2; DE 30 42 895 C2).
It is the object of the present invention to devise a device for piping, of a general type described hereinabove, which device has high operating safety and meets the highest requirements for quality of the fluid products processed in it, which device overall, including its anti-mixing valves, is easy and inexpensive to fabricate, and which, under all practically occurring arrangement variants of the valve distributor tree in relation to the associated process aggregate or tank of the process apparatus, in the respective valve distributor tree, reproduces to the extent possible, the same technological conditions and condition parameters as in the process aggregate or tank. It is a further object of the invention to suggest a method of operating a described device, which method, to the extent possible, provides the same technological conditions and condition parameters in the valve distributor tree as in the tank or process aggregate.